Variable delivery oil pumps



March 30, 1965 YosHKAzu KUZE VARIABLE DELIVERY OIL-PUMPS 5 Sheets-Sheet l Filed Aug. 27, 1962 INVENTOR f 77( 9*WATTORNEYS March 30, 1965 YosHlKAzU KuzE 3,175,509

VARIABLE DELIVERY OIL PUMPS Filed Aug. 27, 1962 3 Sheets-Sheet 2 Erg 4 1 8 F1g .ll7 Y l Q8 )gg I P7 40 4I f7 mi I (D 20r\\\\\\ a' Q l-, i? Q2 INVENTOR March 30, 1965 YosHlKAzu KUzE VARIABLE DELIVERY OIL PUMPS 3 Sheets-Sheet 5 Filed Aug. 27, 1962 INVENT OR ATTORNE United States Patent 3,175,569 VARIABLE DELIVERY UIL PUMPS Yoshilxazu Kuzc, 64 Chidori-clio, Chofu, Gta-itu, Tokyo,

This invention relates to improvements in pumps for supplying various amounts of oil in response to changes in the pressure produced in any load such as a hydraulic machine, uid running device, oil motor for driving wheels etc.

An object of the invention is to provide a variable delivery oil pump which is operable to automatically change the angle of inclination of a swash plate so as to change the amount of oil to be delivered from the maximum to zero in response to the pressure of a load at the exhaust side Variable up to a predetermined maximum pressure, and which is simple in construction, operable in high pressure and high speed, small in size, light in weight and extremely eiiicient in operation.

For a better understanding of the invention reference is taken to the accompanying drawings, in which,

FIG. 1 is a longitudinal sectional View of the variable delivery oil pumps and of an operating valve thereof and also shows a piping system connected between the oil pump and the operating valve;

FIG. 2 is a longitudinal sectional view of said operating valve in the operated condition;

FIG. 3 is a front elevation of an oil supply manifold;

FIG. 4 is a front View of a valve plate;

FIG. 5 is its longitudinal sectional View;

FIG. 6 is a longitudinal sectional view of an oil distributor block adapted to fit therein the Valve plate at the inner end of the oil supply member;

FIG. 7 is its front elevation seen from the left side thereof;

FIG. 8 is a front elevation of a cylinder block arranged in opposition tothe oil distributor block and the valve plate seen from the right side thereof;

FIG. 9 is its longitudinal sectional view showing also the oil distributor block by chain lines;

FIG. 10 is a perspective View of one of two pieces constituting a bearing member for supporting a free end of a movable swash plate;

FIG. l1 is a plan View of an inner end of a diierential piston rod slidably enclosed in the bearing, member; and

FIG. 12 is a longitudinal sectional View of another embodiment of the variable delivery oil pump according to the invention.

The essentials of the invention lie in an axial type variable delivery oil pump that provision is made of a swash plate 3 pivotally mounted in a casing 2 in a manner such that it can be moved with variable inclinations by means of diametrically arranged pins 1, 1, the free end 5 of the swash plate 3 being operatively connected to a differential piston 6, two chambers 7, 8 formed in a cylinder by the piston 6 are made in communication through dashpot holesv 9, 1'0 with the exhaust side 25 of the pump, respectively, and provision is made of a spring 11 adapted to aid the side of the piston 6 having a smaller pressure receiving area formed by a piston rod 35 having a larger diameter. The oil in an oil tank T is fed through a low pressure feed pump p and a check valve v to an oil supply member 12 of the pump according to the invention. Thus, the oil enters through several apertures 16 formed in a disc part of a valve plate 14 into a space at the back of a plunger piston 17 shown at the upper side of FIG. l. The valve plate 14 is fitted around m 3,175,539 Patented Mar. 30, 1965 ice eccentric pin 13 formed at the inner end of the oil supply member 12. The oil supply member 12 is secured to one half of a casing 19 in alignment with and in opposition to an input shaft 18 integral with a cylinder block 20. The eccentric pin 13 is eccentrically arranged with respect to the axis of the oil supply member 12, so that the open inner end of plunger pistons 17 is made in communication with a space formed outside of the rim of the valve plate 14 in response to the rotation of the cylinder block 20. The oil is forced into a crescent shaped space 22 formed between the periphery of the valve plate 14 and an oil distributor block 21 by the thrust action of the swash plate 3. The oil distributor block 21 is secured to the cylinder block 20 and rotates together with the latter. Thus, an oil exhaust means 24 iitted around the oil supply member 12 constitutes a bearing in opposition to and corresponding to a bearing 23 for supporting input shaft 1S. The oil exhaust means 24 communicates with an oil outlet hole 25 and is fitted around the oil supply member 12 so as to form an annular space 26 therebetween and secured to the casing 19. The oil distributor block 21 is rotatably mounted on the small diameter part of the oil exhaust means 24 to form at its central inner peripheral surface an annular groove 27 having a large width. The oil in the crescent shaped space 22 enters through a number of radial holes 28 formed in the oil distributor block 21 into the annular groove 27 where the oil serves to lubricate the contact surfaces of the small diameter portion of the oil exhaust means 24 with the oil distributor block 21. Then, the oil passes into a number of radial holes 29 formed at the inner end of the oil exhaust means 24 into the annular space 26 formed between the oil exhaust means 24 and the oil supply member 12. Then, the oil passes through the oil outlet hole 25 to a load L and at the same time through an operating valve 30 to both of the chambers 7, 8 of the cylinder of the above mentioned differential piston 6, as shown by arrows. That is, provision is made of the operating valve 30 included in the piping system of the pump, as shown in FIG. 1. FIG. l shows a normal operating condition of the operating valve 30. If a valve rod 31 is pushed downwards against the action of a spring 32, as shown in FIG. 2, the oil pressure is supplied to a chamber 34 enclosing a piston rod 33 having a smaller diameter and applied to the side of the piston 6 having a larger pressure receiving area 8. The oil in a chamber 7 having a smaller pressure receiving area and located in opposition to the piston 6 is made in communication through the operating valve 30 shown in FIG. 2 with the oil tank T. The piston 6, thus, no more acts as a differential piston and moves towards the right side. The end 36 of the piston rod 35 extending through the cylinder is connected to a plug portion 37 projecting from the free end 5 of the swash plate 3 and forms with the latter a safety device which renders it possible to move the swash plate 3 so as to change the angle with a vertical line from a shown in FIG. l to zero and rapidly stop the feed of oil to the load L. Relief valves V1 and V2 are included in the exhaust piping systems of the pump and of the feed pump p, respectively, for the purpose of relieving the abnormal high oil pressure. The swash plate 3 is movably supported by means of roller bearings and thrust ball bearings (not shown), so that it can be reciprocably moved with diderent inclined angles. The position of the swash plate 3 where its inclination with respect to a vertical line is zero is determined by engagement of a shoulder 38 formed at the free end of the swash plate 3 in opposition to the free end 5 thereof with a projection 39 formed at the inside wall of the casing 2. The plug 37 projecting from the free end 5 of the swash plate 3 is sphere-like shaped and embraced between two spherical of the swash plate 3 in a smooth manner.

The operation ofthe variable delivery oil pump according to the invention is as follows:

If the pump is started to operate, its exhaust oil pressure becomes highiin response to the increase of the pressure caused by the load L. If the operating valve is operated, the oil pressure is fed through the dashpot holes 9, 10 to the two chambers 7, 8 of the piston 6 having different pressure receiving areas, so that the piston 6 is moved in response to the difference of the pressures applied to both ends of the piston 6. The piston 6 moves to the side of the piston rod having a larger diameter and lesser pressure receiving area to move the swash plate 3 through the plug 37 projecting from the free end 5 of the swash plate 3 and engaging with the end 36 of the piston rod 35 extending through `the cylinder against the action of the spring 11 such that the inclined angle a of the swash plate 3 becomes decreased. Thus, the exhaust oil is inversely decreased automatically in response to `the increase of the pressure, thereby constituting a socalled variable deliveryoil pump. The reason why the above mentioned differential piston mechanism is used in the invention is as follows:

A conventional type piston has vdisadvantages that'it requires a very strong spring for the purpose of forcing back the piston against a predetermined maximum exhaust pressure 'of the pump, which results in the correspending part of the piston being massive in construction. The differential piston improved by the invention has the feature that if the difference of the diameters of the piston rods 33, 35 at opposite sides thereof is so selected use may be made ofthe spring 11 which is only suhcient to resist the force produced by the pressure difference at the areas ofthe opposite sidesV of the piston times a given maximum exhaust pressure. Such feature together with the high speed operation makes the piston smaller in size. That is, the variable delivery oil pump according to the invention is operable at high speed, small in size, light in Weight and,V particularly, ,adapted for use in supplying a high pressure oil. -As'to the detailed constructional features, the valve plate 14 adapted to effect a valve action receives the oil pressures at the front and back sides thereof, said oil pressures existing both in the exhaust sideyandv in the suction side of the pump, so that the valve plate 14 is prevented from being subjected to any eccentric force and maintained in a balanced condition. The valve plate 14, therefore, does not become worn at all and can resist both the high pressure and high speed rotation. The oil distributor block 21 is supported in the floated condition by the small diameter end portion of the oil exhaust means 24 by the aid of the oil film produced by the high pressure exhaust oil and filled in the annular groove 27 at the center of the oil distributor block 21, so that the oil distributor block 21 doesfnot nake a direct contact Vwith the small diameter end portion of the oil exhaust means 24, thereby constituting a bearing member which resists against a heavy load and a high speed operation, which could not be attained by any conventional metal bearing. Moreover, the high speed operation of the pump may be stopped by manually operating the operating valve 30. Thus, the pump according to the invention is adapted for use in the operation under ahigh pressure and ina high speed. I

As can be seen fromV the above,'the variable delivery oil pump according to the invention can easily be manufactured and is small in size, light in weight and particularly adapted for use in a high exhaust pressure and high speed operation and applicable to various kinds of driving machines such, for example, as a hydraulic machine, fluid running device, oil motor for driving wheels etc.

Various other modications may be made without departing from the spirit of the invention.

What I claim is:

l. Variable delivery fluid pump comprising a casing, a fluid supply member for receiving uid under pressure disposed in said casing, valve plate means having an aperture therein eccentrically mounted on said fluid supply member, tiuid exhaust means having uid exhaust passages disposed therein mounted on said fluid supply member, a iiuid distributor block having fluid distributing passages therein rotatably mounted on a portion of said fluid exhaust means so that said fluid distributing passages communicate with said fluid exhaust passages, a cylinder block having cylinders therein mounted on said Huid distributor block, piston meansreciprocably mounted in said cylinders, said valve plate means being disposed between said fiuid distributor block and said cylinder block to close part of said fluid distributing passages and to allow communication of part of said cylinders lwith another part of said fluid distributing passages, means mounted to said cylinder block to rotate same, swash plate means reciprocably mounted in said casing adjacent said cylinder block so that said piston means engage said swash plate means, differential piston means` operatively connected to said swash plate means and including piston rods one being of larger diameter than the other, spring means engaging said differential piston means in a direction to aid the smaller of the piston rods, and means for interconnecting the differential piston means and the fluid exhaust means to supply iiuid to said differential piston means to control movement of the swash plate means and the delivery of the fluid from the pumps.

2. Variable delivery lluid pump according to claim 1 wherein said interconnecting means includes valve means which when in a normalposition maintains said dilferential piston means in a variable controlling condition and when in an operated position maintains said swash plate means in a vertical position with respect to the axis of said casing. f

3. In a variable delivery fluid pump, casing means, means to supply uid into said casing means, rotary cylinder means having piston means reciprocably mounted therein disposed in said casing means, valve plate means eccentrically and rotatably mounted on said fluid supply means adjacent said cylinder means and held by said uid to supply said fluid to part of said piston means,

Vexhaust means connected to said valve plate means to receive fluid from another part of said piston means, swash plate means pivotally connected to said casing means adjacent said cylinder means so that said piston means engage said swash plate means, differential piston means operatively connected to said swash plate means to move said swash plate means between an inclined and vertical position with respect `to the axis of said casing means thereby controlling the delivery of the uid from the pump, and means interconnecting said differential piston means and said exhaust means to supply liuid to said differential piston means to control same.

References Cited by the Examiner UNITED STATES PATENTS 2,273,468 2/ 42 Ferris 103--161 2,360,025 10/44 Wahlmark 103-162 2,409,185 10/46 Blasutta 103-162 2,648,312 8/53 Tucker et al 103-161 2,901,979 9/59 Henrichsen 103,-162 2,945,449 7/60 Febvre et al 103--162 3,124,008 3/64 Firth et al. 103--162 LAURENCE V.- EFNER, .Primary Examiner. 

1. VARIABLE DELIVERY FLUID PUMP COMPRISING A CASING, A FLUID SUPPLY MEMBER FOR RECEIVING FLUID UNDER PRESSURE DISPOSED IN SAID CASING, VALVE PLATE MEANS HAVING AN APERTURE THEREIN ECCENTRICALY MOUNTED ON SAID FLUID SUPPLY MEMBER, FLUID EXHAUST MEANS HAVING FLUID EXHAUST PASSAGES DISPOSED THEREIN MOUNTED ON SAID FLUID SUPPLY MEMBER, A FLUID DISTRIBUTOR BLOCK HAVING FLUID DISTRIBUTING PASSAGES THEREIN ROTATABLY MOUNTED ON A PORTION OF SAID FLUID EXHAUST MEANS SO THAT SAID FLUID DISTRIBUTING PASSAGES COMMUNICATE WITH SAID FLUID EXHAUST PASSAGES, A CYLINDER BLOCK HAVING CYLINDERS THEREIN MOUNTED ON SAID FLUID DISTRIBUTOR BLOCK, PISTON MEANS RECIPROCABLY MOUNTED IN SAID CYLINDERS, SAID VALVE PLATE MEANS BEING DISPOSED BETWEEN SAID FLUID DISTRIBUTOR BLOCK AND SAID CYLINDER BLOCK TO CLOSE PART OF SAID FLUID DISTRIBUTING PASSAGES AND TO ALLOW COMMUNICATION OF PART OF SAID CYLINDERS WITH ANOTHER PART OF SAID FLUID DISTRIBUTING PASSAGES, MEANS MOUNTED TO SAID CYLINDER BLOCK TO ROTATE SAME, SWASH PLATE MEANS RECIPROCABLY MOUNTED IN SAID CASING ADJACENT SAID CYLINDER BLOCK SO THAT SAID PISTON MEANS ENGAGE SAID SWASH PLATE MEANS, DIFFERENTIAL PISTON MEANS OPERATIVELY CONNECTED TO SAID SWASH PLATE MEANS AND INCLUDING PISTON RODS ONE BEING OF LARGER DIAMETER THAN THE OTHER, SPRING MEANS ENGAGING SAID DIFFERENTIAL PISTON MEANS IN A DIRECTION TO AID THE SAMLLER OF THE PISTON RODS, AND MEANS FOR INTERCONNECTING THE DIFFERENTIAL PISTON MEANS AND THE FLUID EXHAUST MEANS TO SUPPLY FLUID TO SAID DIFFERENTIAL PISTON MEANS TO CONTROL MOVEMENT OF THE SWASH PLATE MEANS AND THE DELIVERY OF THE FLUID FROM THE PUMPS. 